Question: What is the greatest common factor of $4$ and $16$ ? Another way to say this is: $\operatorname{gcf}(4, 16) = {?}$
Solution: The greatest common factor is the largest number that is a factor of both $4$ and $16$ The factors of $4$ are $1$ $2$ , and $4$ The factors of $16$ are $1$ $2$ $4$ $8$ , and $16$ Thus, the greatest common factor of $4$ and $16$ is $4$. $\operatorname{gcf}(4, 16) = 4$